Table 4

 Epidermal changes in psoriasiform dermatoses

HyperkeratosisParakeratosisAcanthosisSuprapapillary plateMicroabscess formationGranular cell layer changesSpinous cell layer changes (table 6)Basal cell layer changes
*Parakeratotic mounds at the edge of follicular ostia.
BVs, blood vessels; LSC, lichen simplex chronicus; MF, mycosis fungoides; PLC, pityriasis lichenoides chronica; PR, pityriasis rosea; PRP, pityriasis rubra pilaris; +, present; −, absent.
Psoriasis+DiffuseRegularThin+Decreased or absentIncreased mitoses; minimal spongiosis–
Drug reaction+FocalRegular and irregularNormal or thick−NormalSpongiosis; eosinophilic infiltrateInflammatory cell exocytosis; single keratinocyte necrosis
Chronic allergic/contact and atopic dermatitis+Focal; crust may be presentIrregularNormal or thick–NormalSpongiosis; eosinophilic infiltrate–
Fungal infectionCompactFocal; crust may be presentIrregularNormal or thick−NormalOccasional neutrophilic exocytosis;–
LSC+Focal; thick crustRegular or irregularThin or thick−Thickened; hypergranulosis±minimal exocytosis–
Scabies+Focal or diffuseIrregularNormal or thick−NormalExocytosis; eosinophilic spongiosis–
Seborrheic dermatitis and HIV dermatitis+FocalIrregularNormal or thick−NormalSpongiosis; lymphocytic and neutrophilic infiltrate–
PRPCompactShoulder parakeratosis*; alternating orthokeratosis and parakeratosisRegular or irregularNormal or thick−NormalSpongiosis; lymphocytic exocytosis; rare acantholysisOccasional vacuolar change
PR+FocalIrregularNormal or thick−NormalSmall foci of spongiosis; lymphocytic exocytosisOccasional necrotic keratinocytes
Syphilis+FocalRegular or irregularNormal or thick−NormalLymphocytic and neutrophilic exocytosisInterface change
PLC+Caps of parakeratosisIrregularNormal−NormalMild spongiosis, lymphocytic exocytosis; necrotic keratinocytesNecrotic keratinocytes
MF+FocalRegular or irregularNormal−NormalMinimal or no spongiosis; ±Pautrier microabscessAtypical lymphoid cells lining the dermo–epidermal junction